With improvement of display technology, more and more Active Matrix Organic Light Emitting Diode (AMOLED) display panels are available on the market. Compared with the conventional Thin Film Transistor Liquid Crystal Display (TFT LCD), the AMOLED has advantages of low power consumption, low manufacturing cost, self-luminous, wide viewing angle and fast response, etc. At present, traditional LCD displays have been gradually replaced in display fields such as mobile phones, PDAs, digital cameras and the like. Unlike TFT LCDs which use a steady voltage to control the luminance, the AMOLED requires a steady current to control the light emission.
In an existing pixel circuit for driving the emission of the OLED, when a driving transistor drives the light emitting device OLED to emit light, a threshold voltage Vth of the driving transistor in each pixel circuit may be non-uniform due to following reasons: the luminance of the OLED being quite sensitive to variation of the driving current of the OLED, the driving transistor being not exactly the same in the manufacturing process, deviation of the process manufacture and aging of the device, and temperature changes during the operation, or the like. Therefore, a current of the OLED flowing through each pixel point may be different, which causes uneven display brightness and in turn affects the display effect of the whole image.
It should be noted that, information disclosed in the above background portion is provided only for better understanding of the background of the present disclosure, and thus it may contain information that does not form the prior art known by those ordinary skilled in the art.